Glass-thickness gauge



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1 w. o. LYTLE GLASS THICKNESS GAUGE- 1923 I5 Sheets-Sheetv 1 Filed Aug. '7,

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Aug 59 1924 W. O. LYTLE GLASS THICKNESS GAUGE Filed Aug. 7, 1923 3 Sheets-Sheet 2 l --li:i K AL u Aug. 5, 1.924. 1,503,545

W. C. LYTLE GLAS S THI CKNES S GAUGE Filed Aug. 7, 1923 5 Sheets-Sheet 5 45 I INYENTOR 39 of the glass sheet.

Fatented Au ram omen]; LYTLE, or roan crrv, rnnnsvnvsnm,nssrononl T PITTS- ZBD'BGH PLATE GLASS comrnivr, a CORYOBATION or rannsrnv.

cmss rizrcmvnss canon Application filed august To all whom/ct may canoe m:

\ Be .it known that 1, WILLIAM 011mm) Y LYTLE, a citizen of the United States, and a. resident of Ford City, in the county of Armstrong and State of Pennsylvania, have made anew and useful invention in Improvements inGless-Thicmess Gauges, of which the following is aspecificatioir. Q

The invention relates to a device for inch. in eating the thickness of sheet glass, and has for its primary object the provision of animple deviceby means of which the thiclmese of a glass sheet may be accurately determined at anyvpoint by merely applying the it gauge to the top surface of-the sheet, and observi the readin on the'fscale of the device. xiefly-state ,this isaccomplished byan optical method, a beam of light projected downwardly through the glass fit? sheet at an angle'thereto, and then its upwardly from the lower surface of the glass onto the scale of the instrument, 'vfiich may be observed through an eye piece. Ehe point at which the reflected light strikes the at scale will vary directly as the distanceof the lower reflecting surface of the glass from the scale, so that by calibrating the length of the scale graduation, direct and accurate readings may be obtained as to the thickness One embodiment ofthe invention is illustrated in the accompanying drawings wherein: p

, Figure 1 is a plan view of the a paratus. Fig. 2 is a section on the line Ill-i l of Fig. 1 showing the device in use. Fig. 3 is a. ver-. tical section through a modification. Fig. 4 is a side elevation of the Fig. 3 construction. Fig. 5 is a plan View. Figs. 6, 7 and 8 are detailed views on an enlarged scale of the base plate of the device ofFig. 4. Fig. 9. is a side elevation of a modification. Fig. 10 is a plan view ofthe lower end of the observation element of Fig. 9. F ig. 11 is a plan view of the upper end of the observation' element of Fig. 19. And Figs. .12 and 13 are side elevations of still other modifications.

Referring to the drawin s, 1 is a plate of glass whose thickness is to as measured; 2 is a metal plate constituting a portion, of the base of the apparatus and adaptedto contact with the upper surface of the glass plate 1; 3 is a plate having a window or opening therethrough in which are mounted the transparent plates 4; and 5, the first of which 7, 1923. Eerie! No.-656,22a.

is provided with a scale 6(Fig. 1) 7 is an observation tube provided withthe ca 3 carrying the magnifying lens 9; 10 is a attery; i1 is an electric light; and 12 is a sheet of-co pper or other 0 aque material prov: ed w1th a slot 13 for t e passage of a heam of light from the lam throu h the plate whose thickness is to he gage. Secmedto the base are a pair of supporting members 14 and 15 for carrying the tube 7, battery 10 and the lamplfi, the ry f 1; clamped in position by means of the s p niember 16 and the lamp by means of the clamp 1'? pivoted to the member 14 as in-.

.dicated at 18. Suitable connections from the -battery to the'lamp terminals are made,-

one of which, the wire 19 is indicated as attach ed to the Contact 20 opposite the end of; the lamp.

The-slot 13 in the member 12 is prefer ably made in the form of an arrow as indiceted in Fig. 1, and is positioned so that the light passing through this slotbe shown onthelass plate a which carries the scale at the si eof such scaleasindicated by the dotted arrow at 21 in Fig. 1. The beam of lighttravehng down througgthe plate 1 is indicated in Fig. 2 by the e22, vhile the reflected is indicated by the line 23. It will he seen that the point at which the beam 23 engages the 'male plate a will depend upon the thickness of the plate 1. The thickerthe plate, the further to the right will be the point at which the beam of light passes through the scale plate. By properly calibrating the graduations, direct readings as to the thickness of the glass plate towhich the instrument is applied may be secured. On the scale, as illustrated,

.graduations are in thirty-seconds of an inch. The scale is observed through the tube 7 which-,is blackened upon its interior and provided with theeye piece having the Sign 24, the lens 9 serving to magnify thescale and increase the clearness of theiob erviation.,, In order to illuminate the scale,- the end of the scale plate 4 is a polished bevel I 7 as indicatedat 25, and is so positioned that a beam of lightfrom the lamp 11 strikes this bevel and is reflected longitudinally through the plate 4. This is a valuable feature, in that it makes the scale visible even against a black background, such as a cutting table top.

in use the instrument is plaoed upon a sheet of glass to be measured as indicated in Fig. 2 and the thumb piece 26 of the battery is operated to switch on the current to the lamp 11. This gives the beam of light 22 which strikes the lower surface of the plate 1 and is reflected along the line 23 to the scale plate, where the beam of light shows form ,of apparatus up in the form of the arrow 21 (Fig. 1) which may be readily observed throug the slot'24 of the observation tube 7, the clearness of the observation being increased b the reason of the light reflected longitudinally of the scale plate by means of the bevel 25 as heretofore explained. The thickness of the sheet at any oint may thus be read ily determined, and the reading may be made as close as one hundredth of an inch or better if desired.

In the modification illustrated in Figs. 3 to 8, provision is made whereby the observation tube may be set at an angle of 90 degrees to the lass plate 27 whose thickness is to be gaged. In this construction, 28 is the observation tube; 29 is the battery for the light 30; 31 is the base plate of the device; and 32 is a retracting member whereby the ray of light indicated by the dotted lines 33 is given a vertical path after it passes the v member 32. As in the other construction, a

pair of plates 34 and 35 are mounted in the base 31, the lower face or the plate 34 bein provided with the scale 36. The end of the plate 34 is provided with a bevel 37 corre sponding in function to the bevel 25 described in connection with the first form of device. The indicating means in this construction is in the form of a slot 38 in the plate 39, the ray of light 36 passing through such slot and being reflected upward through the scale and through the refracting member 32 so that it may be observed through the slot 40 in the eye piece 41. In this construction a small mirror 42 is also employed for increasing the illumination in the plate 34.

Figs. 9 and 10 illustrate/a very simple embodying the invention. The observation member in this case consists of a prism 42 which has'its lower polished face 43 provided with the scale 44 (Fig. 10) and in engagement with the top surface of the glass plate 45 which is tobe measured.

In this construction the indicating means is the toe 46 of the prism 42. The ray of light is provided from the flash light 47 havin the bulb 48, and. the ray of light 49 follows the path indicated in dotted lines in'Fig. 9. In order to magnify the scale, 'theiipper end of the prism is provided with a convex surface 50 and on this surface at the center thereof is a small circle or mark 51 which serves to establish the line of sight. This form of device is not uite so easily read as e other twohereto ore described, but is g to e gaged provided mosses advantageous because of its small size and sim licity.

iig. 12 is a modification corresponding closely to that of Fig. 9, but a slightly different observation element The angle of this element the ray of light 53 strikes against the polished surface 54 and is then reflected verti cally through the upper surface 55 of the observation element, this surface being fiat in this construction and polished and having a mark thereon corresponding to the marl: 51 in the Fig. 9 construction.

Fig. 13 illustrates still another modification in which the angle of the observation element 56 is different from that of Fig. 12 and the upper polished surface 57 of the element lies at an angle to the horizontal instead oi being parallel thereto. ihe dotted line 58 indicates the line of travel of the ray of light.

What I claim is:

1. In combination, a glass thickness gauge comprising an observation member adapted to be placed with its base upon-the plate of glass whose thickness is to be measured, a transparent scale extending transversely of the observation member at its base in parallelism with the surfaceof the glass plate,

an indicating means opposite one end of the 3 scale,

anda source of illumination above the indicating means, the relation of the indicating means and scale being such that e .am of light from the source of illumination will passthe indicating means and be reflected upward from the lower surface of I said plate onto the scale, showing such means upon the scale.

2. In combination,

a glass thickness gauge comprising a base forengagingthe plate to be gaged provided with a transparent sheet having. a scale, an observation member mounted on the base over said transparent sheet, an opaque member provided svith a slit at one end of the transparent sheet, and a source of illumination above the slit, the

relation of the slit and scale being such that a beam of light passing from the sourcebt illumination through the slit will strike the lower surface of said plate and be reflected upward onto said transparent shes, having the scale.

3. In combination. a comprising a base for engaging the plate with a transparent sheet having a scale, an observation member mounted on the base over said transparent sheet, an opaque member provided with a slit at one end of the transparent sheet, a reflecting surface at one end of the transparent sheet, and a source of illumination above said slit and said reflecting surface, the relation of the slit and scale being such that a beam of light passing from the source is so arranged that glass thickness gauge (if illumination through the slit will strike the lower surface of said plate and be reflected upward onto said transparent sheet having the scale, and the angle of said reflecting surface being such that light from source of illumination impinging thereon ,will' be directed longitudinally through the transparent sheet and illuminate it.

4. In combination, a glass thickness gauge comprising a. base for engaging'the plate to be gaged provided with a transparent sheet having a scale, an observation member mounted on the base over said transparent sheet. an opaque member provided with a slit at one 'end' of the transparent sheet, a beveled reflecting surface on the end of the transparent sheet, and a source of illumi nation above the slit,the relation of the slit and scale being such that a beam of light passing from the source of illumination through the slit will strike the lower surface of 'said plate and be reflected upward onto said transparent sheet having the scale.

In testimony whereof, I have hereunto subscribed my name this 25th day of June, 1923.

W. ORLAND LYTLE. 

